Rat α2 acute-phase macroglobulin. Isolation and physicochemical properties

Abstract

1. Rat α2 acute-phase macroglobulin was isolated from turpentine-injected rats by Sephadex G-200 chromatography and ion-exchange chromatography on DEAE-cellulose. This method, since it does not include (NH4)2SO4 treatment, allows the study of the physicochemical as well as the biological properties of the molecule. 2. The purity of the preparation was demonstrated by ultracentrifugation, polyacrylamide-gel electrophoresis, fused “rocket” immunoelectrophoresis as well as double immunodiffusion. 3. The rat α2 acute-phase macroglobulin was characterized in terms of its main physical and chemical properties. Its isoelctric point was determined by isoelectrofocusing to be 4.55; s020,w was 18.4S and E1%/1cm at 278 nm was 6.8. The mol.wt. was determined by light-scattering to be 770000. 4. The amino acid content was compared with that of rat α1 macroglobulin and was found very similar. The carbohydrate composition of α2 acute-phase macroglobulin was determined to be: hexose, 4.25%; glucosamine, 3.4%; sialic acid, 2%; fucose, 0.2%. From these results it was concluded that α2 acute-phase macroglobulin, although a typical acute-phase reactant, possesses the characteristic physicochemical properties of α macroglobulins.